Neoglycoproteins preparation, active ester method

Because O-glycosylation can also be accomplished with active esters (e.g., penta-fluorophenyl esters) [11] of Fmoc serine and threonine, the Fmoc technique provides a general method for the synthesis of glycopeptides. Thomsen-Friedenreich antigen glycopeptides and neoglycoproteins have been obtained by this method in preparative amounts [12], In combination with acid-labile polymeric benzyl ester anchors, this Fmoc technique was applied to solid-phase syntheses of glycopeptides [11,13,14]. 

NMR analysis of the product indicate that Tyr and Lys were modified (53). A homobifunctionalp-nitrophenyl ester was proposed for the preparation of neoglycoproteins (26). In this method, one of the active ester groups is used to react with the co-aminoaUcyl glycoside and the product thereof then will be conjugated to a protein or other amino-bearing material. 

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